Here is quite a nice list of time travel paradoxes...
I recall from a few years back the idea that if time travel was possible, and the past mutable, travelling through time would, after a few changes, result in a future where there was no means of time travel, because that's the most stable state to fall into... The DSR model is more a self-pruning reality which erases big chunks of itself if time travel causes issues, and, issues almost always occur... Interesting questions of whether there's cross-dimensional Time Police, who give the odd little nudge, sometimes at the cost of their own continued existences...
I MAY know the book you're talking about?
Here's a snip from a (rather hokey, mostly male-fantasy self-insert, I think) book whose central premise is, 3 friends in the 1970's stumble across the death of someone who has (sort of) time machine. They're able to "salvage" the time machine...and in engineering the damned thing, they become the founding fathers of a whole race of time travelling SuperPeople, somehow based in the distant past.
The book is "Conrad's Time Machine" by Leo Frankowski...theoretically the "first" book in the series, although it's the last one actually written.
QUOTE:
"I'm sorry, but it's the best answer you are going to get, sir. Please consider that these devices will someday be invented by the two of you gentlemen. If you learned about them before you had invented them, you would be messing with the laws of causality, a most unsafe procedure."
"So just what would happen to me if I did break these laws of yours?"
"I haven't the foggiest idea, sir. To the best of my knowledge, there has never been a well-documented case of anyone ever daring to break those laws."
"Then how can you possibly say that breaking them is dangerous? The best you can honestly say is that it is unknown."
"Sir, you haven't taken the time to consider the facts carefully. We have two entire cultures where millions of people have been using time machines for many thousands of years. Thus, there have been untold trillions of opportunities to violate causality. Consider that some of those people were probably dishonest, and that many more of them were doubtless curious. Yet there is not one single verifiable case of violated causality on record. Do you know why?"
"No, I don't."
"Neither do I. The best guess is that nature has some mechanism that corrects these violations. How it does this is unknown. My own thought is the data can also be stated thusly—"There is no one still in existence who has ever violated causality.' Given that, the short of it, sir, is that I prefer existence to its alternative, and therefore I have no intention of ever messing with the laws of causality."
